The invention relates to an inner ring system for an inlet guide vane cascade of a turbomachine. The invention further relates to an inner ring and an intermediate casing for such an inner ring system as well as a turbomachine with such an inner ring system.
Known from EP1 319 844 B1 is an inner ring or bearing ring for a guide vane cascade of a turbomachine. The inner ring is divided axially into a first ring segment and a second ring segment, which, in the mounted state, together form recesses for the mounting of vane roots of guide vanes of the guide vane cascade. For this purpose, the inner ring has a plurality of axial mounting boreholes or openings, by which the two ring segments are screwed together. The mounting of the inner ring occurs in a second stage of a compressor of the turbomachine, so that the inner ring is held by the guide vane cascade.
A drawback of the known inner ring is regarded as the circumstance that, in its mounted state in a turbomachine, it exhibits relatively low mechanical stability and can take up the loads that occur only to a very limited extent. As a result, the inner ring is not suitable, in particular, for an inlet guide vane cascade, that is, for a first stage of a compressor or of a turbine. A compressor or turbine is also understood to mean, in particular, a compressor module or a turbine module of the turbomachine. Here, under certain circumstances, especially high loads can occur, for example, due to impact of a bird. A compressor module can be, for example, a low-pressure compressor, a medium-pressure compressor, or a high-pressure compressor. This applies correspondingly to the turbine module, for which a low-pressure turbine or medium-pressure turbine or high-pressure turbine can be meant. In addition, owing to the relatively low mechanical stability, the relative positioning of the ring segments of the inner ring with respect to each other changes during operation of the associated turbomachine, this entailing, on the one hand, a deterioration of aerodynamic properties and, on the other hand, an increased wear in the region of the mounted vane roots. This high wear leads to correspondingly high maintenance costs.